Unemployment and economic policy in a context of multiple equilibria.

Summary This thesis studies the performance of the labor market in an economy that is likely to have several equilibria, and the implications of such a configuration for economic policy. It consists of four essays, each dealing with a specific aspect of this problem. First, the econometric analysis of time series of unemployment rates in some OECD countries, allowing in particular the identification of regime changes and their characteristics, provides significant evidence in support of the hypothesis of a multiplicity of equilibria. Second, we study the effects of the introduction of a mandatory minimum wage and of an increase in the minimum wage in a static model of imperfect competition with wage bargaining at the firm level, the labor input being heterogeneous. If the increase in the minimum wage is unfavorable to employment, the introduction of a minimum wage in the presence of a multiplicity of equilibria allows the elimination of the Pareto-inferior equilibrium. Third, we also study the implications of the existence of multiple equilibria for economic policies, due to the alteration of the dynamic properties of the economy, through the complete analysis of a dynamic model of imperfect competition with individual wage bargaining and matching frictions in the labor market. Finally, we show through the experimental tool to what extent the introduction of a so-called solar task variable can be a source of coordination failure and inefficiency in an economy with two Pareto-ordered equilibria.